1. Field of the Invention
The present invention relates to an ion scattering spectrometer in which an accelerated ion beam is bombarded on a sample and particles scattered from the sample are measured to analyze the sample, and in particular to an ion scattering spectrometer that enables to analyze a sample placed in a gas.
2. Description of the Related Art
So far, an ion scattering spectrometer is known in which an accelerated ion beam is bombarded onto a sample and particles scattered from the sample are detected to analyze the structure of the sample.
In addition, in such an ion scattering spectroscopy, a time-of-flight analysis method that measures the time-of-flight of the particles to analyze speed (energy) of the particles is known. Such a time-of-flight analysis method carries out energy analysis with the difference of arrival times of the particles scattered simultaneously from the sample. Accordingly, without depending on whether there is an electric charge or not with the particle, the energy analysis can be carried out.
The kind of detector being used in the ion scattering spectroscopy differs according to the energy or the like of the particles to be measured. In general, when particles of low energy (approximately several keV) or of medium energy (approximately several hundreds keV) are measured, a microchannel plate (MCP) is employed. Further, when particles of high energy (approximately several MeV) are measured, a semiconductor detector is employed.
In the aforementioned ion scattering spectrometer, the scattered ions of low energy or of medium energy can be measured with the microchannel plate (MCP) as a detector. In this case, in order to operate well a detector consisting of this microchannel plate (MCP), the surroundings of the detector is required to be a high vacuum of approximately 10xe2x88x927 Torr or less. Further, even when a semiconductor detector capable of being used in a low vacuum (approximately 0.1 Torr) is employed, if a gas being used reacts with the detector, the surroundings of the detector is required to evacuate to a high vacuum. Accordingly, so far, the surroundings of a sample is also made a high vacuum according to this, and measurement of the sample is carried out under a high vacuum.
As described above, a conventional ion scattering spectrometer, in particular, an ion scattering spectrometer of low energy or medium energy analysis measures a sample under a high vacuum.
However, if an ion scattering spectroscopy method can be employed in analysis of a sample under a reduced atmospheric pressure (for example, approximately from 10xe2x88x922 to 10xe2x88x923 Torr) where a certain amount of gas exists, for example, in analysis of a state of a film during vapor-phase deposition or the like, an ion scattering spectrometer can be employed in monitoring a film during film formation. Thus, the range of application of the ion scattering spectrometer can be widened remarkably.
This invention is disclosed in Japanese Patent Application No. 10-151245 filed on Jun. 1, 1998, and the entire disclosure thereof is incorporated herein by reference.
An object of the present invention is to provide an ion scattering spectrometer that is capable of analyzing a sample placed in a gas atmosphere such as a gas for film formation.
In the present invention, an ion scattering spectrometer in which an ion beam generated at an ion source is accelerated by an accelerator to irradiate a sample placed in a sample chamber, and particles scattered from the sample are measured by a detector disposed at a prescribed position, comprises:
a gas introducing means for introducing a prescribed gas into the sample chamber for treating the sample;
a first exhaust means for exhausting the sample chamber to make the sample chamber an atmosphere of the prescribed gas of a prescribed reduced pressure;
an orifice disposed between the sample chamber and the detector; and
a second exhaust means for exhausting a neighbor of the detector to make the neighbor of the detector an atmosphere of a higher vacuum than the sample chamber.
Further, in the aforementioned ion scattering spectrometer of the present invention, the orifice comprises a first orifice disposed at the sample chamber side, and a second orifice disposed toward the detector side than the first orifice.
Still further, the aforementioned ion scattering spectrometer of the present invention comprises a third exhausting means for exhausting a region between the first orifice and the second orifice.
Further, in the aforementioned respective ion scattering spectrometers of the present invention, the detector is disposed at a prescribed distance apart from the sample and constituted to analyze the energy of the scattered particles.
Still further, in the aforementioned respective ion scattering spectrometers of the present invention, the gas introducing means is constituted to introduce a prescribed gas for film formation into the sample chamber and to form a prescribed film on the sample.